Rosário Monteiro

CHRONIC INFLAMMATION IN OBESITY AND THE METABOLIC SYNDROME

The increasing incidence of obesity and the metabolic syndrome is disturbing. The activation of inflammatory pathways, used normally as host defence, reminds the seriousness of this condition. There is probably more than one cause for activation of inflammation. Apparently, metabolic overload evokes stress reactions, such as oxidative, inflammatory, organelle and cell hypertrophy, generating vicious cycles. Adipocyte hypertrophy, through physical reasons, facilitates cell rupture, what will evoke an inflammatory reaction. Inability of adipose tissue development to engulf incoming fat leads to deposition in other organs, mainly in the liver, with consequences on insulin resistance. The oxidative stress which accompanies feeding, particularly when there is excessive ingestion of fat and/or other macronutrients without concomitant ingestion of antioxidant-rich foods/beverages, may contribute to inflammation attributed to obesity. Moreover, data on the interaction of microbiota with food and obesity brought new hypothesis for the obesity/fat diet relationship with inflammation. Beyond these, other phenomena, for instance psychological and/or circadian rhythm disturbances, may likewise contribute to oxidative/inflammatory status. The difficulty in the management of obesity/metabolic syndrome is linked to their multifactorial nature where environmental, genetic and psychosocial factors interact through complex networks.

Xanthohumol inhibits inflammatory factor production and angiogenesis in breast cancer xenografts

Xanthohumol (XN), a natural polyphenol present in beer, is known to exert anti‐cancer effects. However, its precise mechanisms are not yet clearly defined. The aim of this study was to investigate the effect of oral administration of XN in breast cancer xenografts in nude mice. Proliferation and apoptosis were first examined in MCF7 cell cultures after incubation with XN by trypan blue exclusion assay, [3H]‐thymidine incorporation, KI67 immunostaining and TUNEL. Morphological and histological characteristics of tumours from XN‐treated or control (vehicle‐treated) mice were compared. Immunohistochemistry for proliferative, inflammatory and endothelial cell markers was performed and activation of nuclear factor kappa B (NFκB) pathway was assessed by ELISA. In vitro MCF7 cell proliferation decreased in a dose‐dependent manner. Oral administration of XN to nude mice inoculated with MCF7 cells resulted in central necrosis within tumours, reduced inflammatory cell number, focal proliferation areas, increased percentage of apoptotic cells and decreased microvessel density. Anti‐angiogenic effects of XN were further confirmed by immunoblotting for factor VIII expression in XN‐treated tumours as compared to controls. Decreased immunostaining for NFκB, phosphorylated‐inhibitor of kappa B and interleukin‐1β were also observed as well as a significant decrease in NFκB activity to 60% of control values. These novel findings indicate that XN is able to target both breast cancer and host cells, namely inflammatory and endothelial cells, suggesting its potential use as a double‐edge anti‐cancer agent. J. Cell. Biochem. 104: 1699–1707, 2008.

11β-Hydroxysteroid dehydrogenase type 1: relevance of its modulation in the pathophysiology of obesity, the metabolic syndrome and type 2 diabetes mellitus.

Recent evidence strongly argues for a pathogenic role of glucocorticoids and 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1) in obesity and the metabolic syndrome, a cluster of risk factors for atherosclerotic cardiovascular disease and type 2 diabetes mellitus (T2DM) that includes insulin resistance (IR), dyslipidaemia, hypertension and visceral obesity. This has been partially prompted not only by the striking clinical resemblances between the metabolic syndrome and Cushings syndrome (a state characterized by hypercortisolism that associates with metabolic syndrome components) but also from monogenic rodent models for the metabolic syndrome (e.g. the leptin‐deficient ob/ob mouse or the leptin‐resistant Zucker rat) that display overall increased secretion of glucocorticoids. However, systemic circulating glucocorticoids are not elevated in obese patients and/or patients with metabolic syndrome. The study of the role of 11β‐HSD system shed light on this conundrum, showing that local glucocorticoids are finely regulated in a tissue‐specific manner at the pre‐receptor level. The system comprises two microsomal enzymes that either activate cortisone to cortisol (11β‐HSD1) or inactivate cortisol to cortisone (11β‐HSD2). Transgenic rodent models, knockout (KO) for HSD11B1 or with HSD11B1 or HSD11B2 overexpression, specifically targeted to the liver or adipose tissue, have been developed and helped unravel the currently undisputable role of the enzymes in metabolic syndrome pathophysiology, in each of its isolated components and in their prevention. In the transgenic HSD11B1 overexpressing models, different features of the metabolic syndrome and obesity are replicated. HSD11B1 gene deficiency or HSD11B2 gene overexpression associates with improvements in the metabolic profile. In face of these demonstrations, research efforts are now being turned both into the inhibition of 11β‐HSD1 as a possible pharmacological target and into the role of dietary habits on the establishment or the prevention of the metabolic syndrome, obesity and T2DM through 11β‐HSD1 modulation. We intend to review and discuss 11β‐HSD1 and obesity, the metabolic syndrome and T2DM and to highlight the potential of its inhibition for therapeutic or prophylactic approaches in those metabolic diseases.

Adipocyte Size and Liability to Cell Death

Obesity constitutes a serious health problem. Inflammation, which has recently been shown to follow adipocyte death, is at the basis of a series of pathogenic complications of obesity. Here we demonstrate, through modelling using the finite element method, that the bigger the adipocyte, the more fragile it becomes to rupture when submitted to common physical forces. This indicates that adipocyte size is an important determinant of cell death. Interventions to prevent adipocyte hypertrophy may, therefore, help to reduce the risk associated with obesity.

Modulation of breast cancer cell survival by aromatase inhibiting hop (Humulus lupulus L.) flavonoids

Hop flavonoids are being regarded as attractive molecules to prevent or treat certain forms of cancer. Studies have focused mainly on xanthohumol, the most abundant prenylated chalcone existing in hops extract. However, during the production of beer, or after its ingestion, xanthohumol originates different metabolites, among which isoxanthohumol and 8-prenylnaringenin. The aim of this work was to study the effect of the prenylflavonoids xanthohumol, isoxanthohumol and 8-prenylnaringenin on the breast cancer Sk-Br-3 cell line proliferation, apoptosis and activity of the enzyme aromatase (estrogen synthase). Aromatase activity was determined by a tritiated water assay, cell proliferation was assessed by [(3)H]thymidine incorporation, sulforhodamine B protein measurement and Ki-67 immunostaining and apoptosis was determined by TUNEL. Our results show that all tested prenylflavonoids were able to inhibit aromatase activity and thus, estrogen formation. Additionally, breast cancer cell line proliferation was decreased and apoptosis induced by all three compounds. The presence of 17beta-estradiol in treatment medium was able to revert the effect of the prenylflavonoids on cellular proliferation. These observations strengthen the idea that hop flavonoids may have anti-breast cancer effects and shed new light on a possible mechanism of action by which these effects occur, namely through their ability to decrease estrogen synthesis.

Effect of polyphenols on the intestinal and placental transport of some bioactive compounds

Polyphenols are a group of widely distributed phytochemicals present in most foods of vegetable origin. A growing number of biological effects have been attributed to these molecules in the past few years and only recently has their interference with the transport capacity of epithelial barriers received attention. This review will present data obtained concerning the effect of polyphenols upon the transport of some compounds (organic cations, glucose and the vitamins thiamin and folic acid) at the intestinal and placental barriers. Important conclusions can be drawn: (i) different classes of polyphenols affect transport of these bioactive compounds at the intestinal epithelia and the placenta; (ii) different compounds belonging to the same phenolic family often possess opposite effects upon transport of a given molecule; (iii) the acute and chronic/short-term and long-term exposures to polyphenols do not produce parallel results and, therefore, care should be taken when extrapolating results; (iv) the effect of polyphenolics in combination may be very different from the expected ones taking into account the effect of each of these compounds alone, and so care should be taken when speculating on the effect of a drink based on the effect of one component only; (v) care should be taken in drawing conclusions for alcoholic beverages from results obtained with ethanol alone. Although most of the data reviewed in the present paper refer to in vitro experiments with cell-culture systems, these studies raise a concern about possible changes in the bioavailability of substrates upon concomitant ingestion of polyphenols.

Estrogen Signaling in Metabolic Inflammation

There is extensive evidence supporting the interference of inflammatory activation with metabolism. Obesity, mainly visceral obesity, is associated with a low-grade inflammatory state, triggered by metabolic surplus where specialized metabolic cells such as adipocytes activate cellular stress initiating and sustaining the inflammatory program. The increasing prevalence of obesity, resulting in increased cardiometabolic risk and precipitating illness such as cardiovascular disease, type 2 diabetes, fatty liver, cirrhosis, and certain types of cancer, constitutes a good example of this association. The metabolic actions of estrogens have been studied extensively and there is also accumulating evidence that estrogens influence immune processes. However, the connection between these two fields of estrogen actions has been underacknowledged since little attention has been drawn towards the possible action of estrogens on the modulation of metabolism through their anti-inflammatory properties. In the present paper, we summarize knowledge on the modification inflammatory processes by estrogens with impact on metabolism and highlight major research questions on the field. Understanding the regulation of metabolic inflammation by estrogens may provide the basis for the development of therapeutic strategies to the management of metabolic dysfunctions.

Persistent organic pollutant levels in human visceral and subcutaneous adipose tissue in obese individuals-Depot differences and dysmetabolism implications

BACKGROUND The role of persistent organic pollutants (POPs) with endocrine disrupting activity in the aetiology of obesity and other metabolic dysfunctions has been recently highlighted. Adipose tissue (AT) is a common site of POPs accumulation where they can induce adverse effects on human health. OBJECTIVES To evaluate the presence of POPs in human visceral (vAT) and subcutaneous (scAT) adipose tissue in a sample of Portuguese obese patients that underwent bariatric surgery, and assess their putative association with metabolic disruption preoperatively, as well as with subsequent body mass index (BMI) reduction. METHODS AT samples (n=189) from obese patients (BMI ≥ 35) were collected and the levels of 13 POPs were determined by gas chromatography with electron-capture detection (GC-ECD). Anthropometric and biochemical data were collected at the time of surgery. BMI variation was evaluated after 12 months and adipocyte size was measured in AT samples. RESULTS Our data confirm that POPs are pervasive in this obese population (96.3% of detection on both tissues), their abundance increasing with age (RS=0.310, p<0.01) and duration of obesity (RS=0.170, p<0.05). We observed a difference in AT depot POPs storage capability, with higher levels of ΣPOPs in vAT (213.9 ± 204.2 compared to 155.1 ± 147.4 ng/g of fat, p<0.001), extremely relevant when evaluating their metabolic impact. Furthermore, there was a positive correlation between POP levels and the presence of metabolic syndrome components, namely dysglycaemia and hypertension, and more importantly with cardiovascular risk (RS=0.277, p<0.01), with relevance for vAT (RS=0.315, p<0.01). Finally, we observed an interesting relation of higher POP levels with lower weight loss in older patients. CONCLUSION Our sample of obese subjects allowed us to highlight the importance of POPs stored in AT on the development of metabolic dysfunction in a context of obesity, shifting the focus to their metabolic effects and not only for their recognition as environmental obesogens.

Xanthohumol Influences Preadipocyte Differentiation: Implication of Antiproliferative and Apoptotic Effects

There is interest in the research of natural compounds that may interfere with the adipocyte life cycle, due to the growing prevalence of obesity and related complications. We aimed at studying the effect of xanthohumol (XN), a Humulus lupulus L. prenylflavonoid, on adipocytes measuring differentiation, proliferation, and apoptosis in 3T3-L1 cells. XN reduced differentiation, as revealed by decreased lipid content and peroxisome proliferator-activated receptor gamma expression, an effect more pronounced when cells were treated before or during differentiation induction. XN also decreased proliferation, as measured by sulforhodamine staining (IC(50) between 26 and 12 microM for 24, 48, and 72 h), and preadipocyte Ki67 expression. Apoptosis was increased in preadipocytes and adipocytes. NF-kappaB activity was stimulated by XN in preadipocytes. Results suggest that XN may reduce adipocyte number, contributing to adipocyte hypertrophy. Taking into consideration the consequences of adipocyte hypertrophy, XN does not seem to improve the metabolic profile associated with obesity.

Red wine increases adipose tissue aromatase expression and regulates body weight and adipocyte size

OBJECTIVE Obesity is an important component of the metabolic syndrome in constituting a risk factor for cardiovascular disease, diabetes, and cancer. Estrogens influence lipid accumulation in adipocytes, acting indirectly or directly on adipose tissue. In this study we aimed to investigate the influence of red wine ingestion on the expression of aromatase (estrogen synthase) in adipose tissue. METHODS Red wine or ethanol solution, in the concentration found in red wine, was provided to Wistar rats as the sole drinking fluid for 8 wk. Food and drink intakes and body weight were monitored throughout treatment and adipocyte size and aromatase expression in the adipose tissue were determined at the end of the experimental period. RESULTS Red wine and ethanol increased aromatase expression in the adipose tissue and red wine decreased adipocyte size (P < 0.05). In addition, animals treated with red wine or ethanol had significantly lower weight gain than controls, despite a similar energy intake. CONCLUSION Thus, the ingestion of red wine may alter the production of estrogens by adipose tissue, body weight gain, and adipocyte size. Some of these red wine effects are attributable to ethanol. This relation among estrogen availability, adipocyte biology, and weight gain is most interesting and deserves further study because it may lead to new strategies to reduce metabolic syndrome incidence.